NuSTAR SPECTROSCOPY OF GRS 1915+105: DISK REFLECTION, SPIN, AND CONNECTIONS TO JETS
Name
Chakrabarty_Nustar spectroscopy.pdf
Size
800.59 KB
Format
Adobe PDF
Checksum (MD5)
e201757d6b5c7e1a129499c307005d18
Author(s)
Miller, J. M.
Parker, M. L.
Fuerst, F.
Bachetti, Matteo
Harrison, Fiona A.
Barret, Didier
Boggs, Steven E.
Christensen, Finn E.
Craig, William W.
Fabian, Andrew C.
Date Issued
September 2013
Journal
The Astrophysical Journal
Publisher
IOP Publishing
Citation
Miller, J. M., M. L. Parker, F. Fuerst, M. Bachetti, F. A. Harrison, D. Barret, S. E. Boggs, et al. “NuSTAR SPECTROSCOPY OF GRS 1915+105: DISK REFLECTION, SPIN, AND CONNECTIONS TO JETS.” The Astrophysical Journal 775, no. 2 (October 1, 2013): L45.
Version
Original manuscript
Abstract
We report on the results of spectral fits made to a NuSTAR observation of the black hole GRS 1915+105 in a "plateau" state. This state is of special interest because it is similar to the "low/hard" state seen in other black holes, especially in that compact, steady jets are launched in this phase. The 3-79 keV bandpass of NuSTAR, and its ability to obtain moderate-resolution spectra free from distortions such as photon pile-up, are extremely well suited to studies of disk reflection in X-ray binaries. In only 15 ks of net exposure, an extraordinarily sensitive spectrum of GRS 1915+105 was measured across the full bandpass. Ionized reflection from a disk around a rapidly spinning black hole is clearly required to fit the spectra; even hybrid Comptonization models including ionized reflection from a disk around a Schwarzschild black hole proved inadequate. A spin parameter of a = 0.98 ± 0.01 (1σ statistical error) is measured via the best-fit model; low spins are ruled out at a high level of confidence. This result suggests that jets can be launched from a disk extending to the innermost stable circular orbit. A very steep inner disk emissivity profile is also measured, consistent with models of compact coronae above Kerr black holes. These results support an emerging association between the hard X-ray corona and the base of the relativistic jet.
MIT Department
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
Terms of Use
Creative Commons Attribution-Noncommercial-Share Alike
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1088/2041-8205/775/2/l45
